The invention relates to textile treatment compositions and, especially, textile softening compositions comprising cationic surfactants and certain highly insoluble carboxylates.
It has long been recognised that certain chemical compounds have the capability of imparting softness to textile fabrics. These compounds, which are known generally as "softening agents", "fabric softeners", or "softeners", have been used both by the textile industry and by housewives in the laundry to soften a finished fabric, thereby making the fabric smooth, pliable and fluffy to handle. In addition to the quality of softness, the fabrics frequently have a reduced tendency to static cling and are easier to iron.
The softening agents which are usually employed in compositions intended for use by the housewife are cationic surfactant compounds, commonly quaternary ammonium compounds having at least two long alkyl chains, for example distearyl dimethyl ammonium chloride. The positive charge on the softening compound encourages its deposition onto the fabric substrate, the surface of which is usually negatively charged.
However, although the above mentioned cationic compounds are highly effective softeners when applied in a rinse solution, there are certain disadvantages associated with their use. For example, the cationic compounds having long alkyl chains are very sensitive to carry over of anionic detergent which tends to neutralize the softening effect because the anionic-cationic complex tends to precipitate out of solution. Also, certain cationic surfactant compounds are expensive and in short supply and it is therefore desirable for commercial reasons, to provide softening compositions having a reduced amount of cationic surfactant compound. Furthermore, softening compositions which comprise predominantly long chain cationic compounds have the disadvantage that the treated fabrics tend to become overloaded with softener and become discolored, greasy or undesirably non-absorbent.
It is known that highly insoluble carboxylates, specifically the heavy metal soaps typified by calcium stearate, have textile softening properties. For instance, British Pat. No. 1,329,416 describes detergent compositions having textile softening effect comprising anionic, nonionic, zwitterionic or amphoteric surfactants and finely dispersed insoluble soaps. Cationic surfactants are generally deemed to be poor detergents, in that they do not remove dirt very well. Thus it is understandable that the inventors of BP 1,329,416 did not include them among suitable detergent actives for their detergent compositions. What they evidently failed to observe, and do not disclose, is that cationic surfactants enhance the deposition and hence the effectiveness of these insoluble soaps upon fabrics.